Traci: I was wondering about the experiment with a baby
and a ringing bell. When the baby got older and heard the bell he
did the thing as when he was younger. Do you know the name of the
baby?

Answer: You may be thinking of Baby "Albert." Albert was an 11-month-old boy who was in an experiment
conducted by American psychologist John B. Watson. Watson was doing an
experiment on emotional response conditioning. At first, Albert liked
playing with a white rat. Later when Albert saw a rat, the experimenters
made a loud noise. This frightened Albert. After a few more times of
pairing the rat with the loud noise, Albert became frightened of just
seeing the rat.

Later on, Albert's fear generalized to anything furry like a rabbit, a fur
coat and dogs. This "experiment" was done many years ago (Watson, J.B.
and Raynor. Conditioned emotion reactions. Journal of Experimental
Psychology, 3:1-14, 1920) and such an experiment would be considered
unethical these days.

H. and C. Approximately how many hairs are on one human head?

Answer: According to The Handy Science Answer
Book (1994) compiled by the Science and Technology Department of the
Carnegie Library of Pittsburgh:

An average person has about 100,000 hairs on their scalp.

Jerry H. What mammal has the largest brain?

Answer: The mammal with the largest brain is the
sperm whale. The brain of the sperm whale can weigh as much as 20 pounds.
Even though the blue whale has a larger body size, the blue whale brain is
about 5 pounds lighter than that of the sperm whale.

Stephanie S. I heard something on the news a while ago. Here's the main plot: Patients are anesthetized and are brought into surgery. However
during the surgery, the anesthesia wears off and the patients feel
everything that's happening to them. BUT they can't say anything or move
anything because they're paralyzed for some reason. I think the term for
this is "surgical awareness." Have you heard of this?

Answer from Dr. Chris B. (anesthesiologist and
Neuroscientist Network member) Awareness during surgery and
anesthesia does occur but is an extremely rare event. The anesthetic does
not "wear off" as the story may have suggested (as an aside, in my
opinion, medical/science stories are reported poorly by the media and are
frequently inaccurate because the media is selling sensation and not
fact. In addition, physicians and scientists are also culpable because
they are willing to make their work sound more
dramatic/important/sensational than it really is).

Anesthetics are given continuously during the surgery but very rarely the
amount given may not be sufficient to produce complete unconsciousness.
This occurs for two reasons; 1) by far, the most common reason is that the
patient does not tolerate the anesthetic (all anesthetics depress the
cardiovascular system) and the anesthesiologist has to turn the anesthetic
down to prevent it from depressing the blood pressure to dangerous levels.
This occurs most commonly in patients who are victims of severe trauma and
are rapidly losing large volumes of blood. 2) awareness can also occur
in patients with a history of alcoholism, sedative/hypnotic abuse (e.g.,
valium, barbiturates, sleeping pills) because their brains are "resistant"
to the sedative effects of the anesthetic.

It should be noted that awareness is distressing, but patients usually
state that pain was not a problem for them, rather it was the distress
of being aware but unable to move for some reason they do not understand.
The reason they can't move is that they were given a "muscle relaxant"
which temporarily paralyzes the muscles. This is done to make it easier
for the surgeons to spread muscles (e.g., abdominal muscles) thus making
it easier to expose the surgical site. At the end of surgery, before the
patient is awakened, the muscle relaxant is reversed.

This question affords another interesting opportunity to see how the
media and business are increasingly intertwined. The story you saw was
most likely the result of an ADVERTISING campaign for a device made by
ASPECT Medical (called the BIS) which they claim is capable of detecting
awareness. To sell this product they need to create a market.
Anesthesiologists have no interest in it because awareness is not a
significant problem (i.e., it is extremely rare and thus there is not much
reason to spend money using this device on millions of patients who are
not at risk of awareness) and this device has NEVER BEEN PROVED TO DETECT
AWARENESS. Thus, to make money the company is basically marketing it to
patients by first telling them (through "stories" like the one you saw)
that awareness is a terrible problem (and needlessly scaring them) but
fortunately they have a solution. Consequently, patients come to their
anesthesiologists requesting that they use this unproved, useless,
expensive device during their anesthetic. Anesthesiologists are thus
"compelled" to buy this instrument to make their patients content.
Consequently, medical costs go up, but that is not a problem for ASPECT
because they reap the financial rewards.

C., L. and E. Can you give us some interesting facts about
the nervous system? We're doing a school project.

M.L. I've been searching for a couple of weeks for a story
I've heard about but can't find a source for. Some researcher thought
that curare was an "anesthetic" so he tried it on himself. Although paralyzed, he could still feel everything. Do you know this anecdote?

M.J. Why do people taking MAO-inhibitors have to be on a tyramine restricted diet?

Answer: MAO (monoamine oxidase) is an enzyme that
breaks down the class of neurotransmitters called the catecholamines.
MAO inhibitors are drugs that block the action of MAO and raise the
catecholamine content within neurons. These drugs are used to treat
depression.

Tyramine is an amino acid found in foods such as cheese, fish and
alcoholic drinks. Tyramine activates the sympathetic nervous system.
Moreover, the action of tyramine is blocked by MAO. Therefore, in the
presence of MAO inhibitors the action of tyramine is intensified and
prolonged. This may result in dangerous hypertension and even cerebral
hemorrhages.

Carolyn. How many muscles are in the human body?

Answer: There are over 600 skeletal muscles in the
human body. Anatomists disagree on the exact number of muscles.
Skeletal muscle makes up about 40% of total body weight.

K.H.: Do you have any information about sleep deprivation in
teenagers and school start times?

Answer: Sleep deprivation IS a huge problem not
only for students, but for adults as well. I will refer you to some
sources of information concerning later school start times and some
schools that have made the switch to later start times. Please see:

Answer: Reuptake refers to the process by which a
neurotransmitter is transported back into a neuron's synaptic terminal.
In other words, after a neurotransmitter is released, it floats into the
synaptic cleft. One mechanism that stops the action of neurotransmitter
is by transporting the neurotransmitter out of the synaptic cleft back
into the terminal.

Robert A. Who discovered diazepam?

Answer: Dr. Leo H. Sternbach of Hoffmann-La Roche (or
just Roche) discovered diazepam. From L.H. Sternbach's chapter titled
"The Discovery of CNS Active 1,4-Benzodiazepines" in the book
The Benzodiazepines: From Molecular Biology to Clinical
Practice edited by E.Costa, Raven Press, New York, 1983:

Near the end of 1959, we found a product that was, in most of the tests,
3 to 10 times as potent as chlordiazepoxide. We hoped that this superior
potency would be associated with other advantages in its clinical spectrum
of activity and selected it for a thorough evaluation. The
pharmacological and toxicological data looked very promising: the
clinical results were equally encouraging and led ultimately near the end
of 1963 to the introduction of diazepam, under the trade name
Valium.

T. Why after sitting down for a long time and you stand up
fast do you sometimes see light spots or stars?

Answer: (from Dr. Chris B., Neuroscientist Network member) The
phenomenon results from hypoperfusion of the brain, particularly the
occipital cortex. But I do not know why one sees "stars" as opposed to
something else. Hypoperfusion results because standing up too rapidly can
result in a decrease in venous return so the heart is not as full as
necessary to maintain adequate cardiac output.

Answer: (from Dr. Ed F., Neuroscientist Network
member) Orthostatic hypotension, decreased blood flow to the brain
because of a gravitational pooling of the blood in the lower extremities.
The baroreceptor reflex minimizes this as it senses the decreased blood
pressure in the aortic arch and responds by sending a signal, through the
brainstem, to increase sympathetic tone in the blood vessels of the lower
legs. This results in a vasoconstriction and helps force more blood to
the upper part of the body.

This reflex is reduced in the elderly and by many medications. That is
why people, especially elderly and those on various heart, blood pressure
medications, antidepressants and any CNS depressant should get up slowly
from a lying or sitting position.

Bonnie M. What is the effect of temperature on the shape of the action potential?

Answer: The effect of temperature is mainly on
ionic permeability of the neuronal membrane. Specifically, sodium
channels open and close faster at higher temperature. Reductions in
temperature lengthen the action potential and slow conduction
velocity...these are the classic experiments of Hodgkin and Katz
(1949).

Z.Z. How many bones are in the human body?

Answer: Babies are born with between 300 to 350 bones.
As people get older, some of these bones fuse together. Most adults have
206 bones:

Laura M. What is the difference between the cerebrum and the cerebral cortex?

Answer: The cerebrum refers to the entire cerebral
hemispheres. The cerebral cortex is the outermost part of the cerebrum.

G.J. Do you think exercise is good for the brain?

Answer: Yes, physical exercise does appear to be
good for the brain. There are been several studies that show that exercise is
beneficial to the brain. In fact, there was a recent experiment in mice
that showed that running can increase the number of nerve cells in the
brain. For a summary of this research, see:

Debbie G. I have always heard a full moon will affect behaviors but
your page contradicts that myth. I have been teaching elementary school
for 19 years and I was wondering if there have been any case studies on
how a full moon affects children's behaviors. I don't keep track of when
it's time for a full moon, but I can usually tell by the way my students
act.

In all of the background research and literature searches I conducted for
the Moonstruck article I did not find any papers that examined the
correlation between the phase of the moon and children's behavior. As I
discussed in the article, there are some problems in the design of these
studies in that they only determine that a correlation does or does not
exist between two variables (i.e., phase of the moon and a change in
behavior). They do not prove that the phase of the moon CAUSES a
particular behavior.

Mark W. What causes "ringing in the ears?"

Answer: Ringing in the ears is called "tinnitus."
All of the causes are not well understood. Some forms of tinnitus are
caused by problems in the inner ear, such as damaged hair cells.
However, some forms may NOT have a peripheral origin. In other words, the
"ringing" may be in the brain, NOT the ear. For more about tinnitus,
please see:

Answer: Dopamine is a neurotransmitter (a
catecholamine type neurotransmitter). It is found in many places in the
central nervous system and has several functions including:

1. Movement: dopamine is produced in the substantia nigra (a part of the
basal ganglia). In Parkinson's disease, dopamine neurons in the
substantia nigra die. This disorder is characterized by tremor, rigidity
and slowness of movement. When the dopamine is restored in the brain by
giving L-dopa, the movement problems in many cases are reduced.

2. Attention: there is some evidence that dopamine is altered in people
with attention deficit disorders.

Answer: In "normal" cases, yes, the action
potential goes in only one direction: toward the axon terminal. However,
an action potential will spread in BOTH directions IF it is started in the
middle of an axon. This can be done by electrically stimulating the
middle of an axon. This is not the normal way action potentials are
triggered. Rather, an axon potential usually starts at the axon hillock
and sequentially depolarizes the neuronal membrane away from where it
started. That is why in normal situations it only travels in one
direction.

A.N. How did neurotransmitters get their specific names? Such as, why is dopamine called dopamine? serotonin? norepinephrine?

Answer (By Neuroscientist Network Member Dr. P.):

a) Background
Catecholamines: This name refers to all organic compounds that contain a
catechol nucleus (a benzene ring with two adjacent hydroxyl residues), a
side chain of two carbon atoms (the b-carbon is closest to the ring, the
a-carbon is distal), and an amine (NH2) group bound to the a-carbon. The
word "catechol" is derived from "catechin," a crystalline substance
extracted from the spiny Asian tree "catechu" (Acacia catechu) which is
used in the preparation of tannins and other brown dyes. Catechin and
catechol are synonymous. In practice, the term catecholamine refers to
dopamine (DA, dihydroxyphenylethylamine) and its metabolic products,
norepinephrine (NE) and epinephrine (E).

b) Neurotransmitters
i. Dopamine (DA): The easiest explanation for dopamine's name is that it
is a selective compression of its chemical name,
dihydroxyphenylethylamine.

To better understand the nomenclature, we can start a couple steps back in
the pathway that leads to the formation of DA. The amino acids
phenylalanine or tyrosine can be the starting compound for the synthetic
pathway. If phenylalanine (a compound similar to the catechol structure
except there are no hydroxyl groups bound to the benzene ring and there is
a carboxyl group (COOH) bound to the same carbon containing the amine
group), an enzyme, phenylalanine hydroxylase, adds an hydroxyl group to
the benzene ring. This product is tyrosine which can also be provided in
the diet directly. The next step in the pathway involves the enzyme
tyrosine hydroxylase, the rate limiting step in the entire process, which
adds a (second) hydroxyl group to the aromatic ring. The resultant
compound is "DOPA" (dihydroxyphenylalanine), a compound with a catechol
backbone as described above. The final step in the synthesis of dopamine
involves the removal of the carboxyl group from the two carbon side chain
of DOPA by the enzyme DOPA decarboxylase. Thus dopamine is composed of the
basic catechol backbone (dihydroxyphenylethylamine) with no substitutions
on the two carbon side chain.

ii. Norepinephrine (NE): Once we've learned how dopamine is formed, the
related catechol compounds fall easily into place. Norepinephrine is
formed from dopamine through the activity of the enzyme
dopamine-b-hydroxylase. Norepinephrine is simply dopamine with an hydroxyl
group added to the b-carbon of the two carbon side chain. See Epinephrine
for the word derivation.

iii. Epinephrine (E): The enzyme phenylethanolamine-N-methyltransferase
adds a methyl group to the amine (NH2) bound to the a-carbon of
norepinephrine.

The derivation of the names epinephrine and norepinephrine are most
likely related to the locale of the highest concentration theses
substances: the adrenal glands. Because the adrenals sit atop the kidneys,
the word epinephrine can be parsed logically: "epi-" means
"upon or close to, "nephr" is the contraction of
"nephro," a prefix designating the kidney, and "ine," a
suffix given to many chemical compounds. The prefix "nor"
designates an unaltered parent compound. This suggests that norepinephrine
was isolated subsequent to epinephrine and, upon discovery of the
relationship, was named appropriately. The parallel nomenclature of
"adrenaline" and "noradrenaline" provide a more obvious
derivation.

Serotonin was named, shortly after its discovery, for its ability to cause
powerful contractions of smooth muscle. Thus it was considered a major
component in the serum responsible for vasoconstriction and high blood
pressure. 2) Acetylcholine is straightforward, formed as product of the
enzyme choline acetyltransferase.

K.B. How much sleep does a third grader need?

Answer: According to the Sleep Well web site (Stanford University Sleep Center):